The increase in vocal symptoms among teachers

The high number of teacher students reporting vocal symptoms led to the question whether the proportion of teachers reporting vocal symptoms has changed within a twelve-year period. In Study IV, data obtained from two cross-sectional studies conducted with an interval of 12 years were compared, and questionnaires were the only methods used. The questionnaires were self-explanatory in both studies and no explanations or definitions were provided. The results of prevalence studies relying on data obtained by questionnaires can be reliable and valid, but the results cannot unambiguously be compared to those of other questionnaire studies because of differences in definitions and criteria (Mattiske et al., 1998). However, the questions concerning the prevalence of vocal symptoms were asked in identical form in the two studies compared in Study IV. The results revealed that more teachers reported vocal symptoms in 2001 than in 1988.

The proportion of teachers reporting two or more vocal symptoms occurring weekly or more frequently during the previous two years had increased from 5% in 1988 to 20% in 2001. The number of teachers reporting symptoms in 2001 is in line with the results of other studies (e.g. Sapir et al., 1993; Russel et al., 1998). It is however lower than the number of daycare center teachers reporting vocal symptoms in a study by Sala et al. (2001) using the same questionnaire. The results of that study showed that 37%

reported two or more vocal symptoms occurring weekly or more frequently. The work

DISCUSSION 37

of daycare center teachers is different from that of schoolteachers, as it involves more reading aloud, more singing and more outdoor activities. The background noise is probably more continuous in daycare centers than in schools. Additionally, Sala et al.

(2001) reported one-year prevalence data for the vocal symptoms in daycare center teachers. In several studies (e.g. Sapir et al., 1993; Smith et al., 1997; Smith, Lemke et al., 1998; Smith, Kirchner et al., 1998) the number of teachers reporting two or more current symptoms seems to be higher than in Study IV. This is in line with the results of Study I, in which the vocal symptoms reported by the teacher students became less frequent over time, that is, the teacher students reported the highest prevalence of vocal symptoms during the past month and the lowest during the previous two years. It is possible that the number of teachers reporting two or more frequently occurring symptoms would have been even higher if the one-month or one-year prevalence had been used instead of the two-year prevalence.

The mean age of the teachers was significantly higher in 2001 than in 1988. The prevalence of voice disorders has been reported to increase with age (Coyle et al., 2001;

Herrington-Hal et al., 1988; Roy, Merrill, Thibeault, Parsa, et al., 2004). The results of a study by Roy, Merrill, Thibeault, Parsa, et al. (2004) evaluating the prevalence of voice disorders in 1243 teachers showed that voice disorders systematically increased with age and were most frequent in the age group of 50-59 years. Thus, the higher mean age of the teachers in 2001 might have had some effect on the results. However, as in 1988, the length of the teaching career was not a significant variable for the prevalence of reported symptoms in the population in 2001. This is in line with the results of some studies in which teaching experience showed little correlation with the prevalence of voice problems among teachers (Pekkarinen et al., 1992; Russel et al., 1998; Sapir et al., 1993; Smith et al., 1997). The discrepancies in the results between the different studies might be due to the different methods used and to differences in the sizes of the study populations.

A surprising result of Study IV was that no significant difference in the prevalence of adverse vocal symptoms reported by male versus female subjects was observed in 2001.

About one fifth of both the female and the male teachers reported two or more symptoms occurring weekly or more frequently. In questionnaire studies, female teachers have been found to report a higher incidence of vocal symptoms than male teachers (Pekkarinen et al., 1992; Roy, Merrill, Thibeault, Parsa, et al., 2004; Russel et al., 1998; Smith, Kirchner et al., 1998). The lack of a gender difference in the teachers in 2001 might be due to low response rates, as only 56% of the teachers returned the questionnaire. Of the respondents, 22% were male. In 1988 the response rate was 80%, and 34% of the respondents were male (Pekkarinen et al., 1992). It is possible that the teachers who felt that they had experienced problems with their voices were more motivated to fill out the questionnaire, which might have had an impact on the results.

Male teachers have been reported to be less likely to respond than females (Russel et al., 1998), and the male teachers who experienced vocal symptoms may have been more active in responding than those who had not experienced any symptoms. On the other

hand, of the more than 42, 400 teachers in comprehensive and upper secondary schools in Finland, only 30% are male (Statistics Finland 2004). On this bases, the return rate from the male teachers cannot be considered to be low. It is possible that voice problems among male teachers are becoming more common. However, no generalizations on this issue can be made on the basis of the results of this study. This question requires further research with larger study populations.

The difference in response rates in 2001 (56%) and in 1988 (80%) might have had some general influence on the results of Study IV. The lower response rate in 2001 compared to that in 1988 may have been due in part to the method of distributing the questionnaires. In 2001, the questionnaires were sent by mail to the schools, and the principal of each school distributed the forms to the teachers. The response rates differed considerably among the schools, and it is possible that the principals’ attitude towards the study and the lack of personal contact between the research team and the principals might have affected the low response rate. The study made in 1988 (Pekkarinen et al., 1992) involved more personal contact with the principals who distributed the questionnaires, which might have had a positive effect. However, in a similar study by Sapir et al. (1993), the response rate was 40%. In that study the rates also varied considerably across schools despite the fact that speech therapists made announcements about the study during teacher meetings and encouraged the teachers to participate. According to Sapir et al. (1993), it cannot be ruled out that the fact that the questionnaires were administered by school administrators might have had an impact on the outcome of the study and that a direct contact with the teachers could have resulted in a higher response rate. A questionnaire study on voice problems among teachers by Russel et al. (1998) had a response rate of 75%. In that study the questionnaires were mailed to the teachers along with a prepaid return envelope, and non-responders received two reminders, which most likely had an effect on the high response rate in that study. The response rate in Study IV might have been higher if the research team had sent the questionnaires to the teachers instead of to the principals.

The fact that more teachers reported frequently occurring vocal symptoms in 2001 than teachers did in 1988 may be due to an increased awareness of voice-related issues.

On the other hand, there was hardly any discussion in the mass media or in the professional journals for teachers in Finland on this issue during the twelve years between the two investigations. Despite a possible increased awareness of voice-related issues among the teachers responding in 2001, the results of the study are still quite alarming. Study IV was a questionnaire study and no phoniatric examination was included. The results of Studies I, II and V revealed that more than half of the students who reported two or more vocal symptoms weekly or more frequently and attended the phoniatric examination had organic findings on their vocal folds. This was also confirmed by the results of a study by Sala et al. (2001), in which all participants underwent a phoniatric examination. Thus, the results of Study IV indicate that voice disorders are a growing problem among teachers.

DISCUSSION 39

One background factor that might have had an effect on the increase in vocal symptoms in 2001 compared to 1988 is related to noisy and/or misbehaving pupils. The increase in reported disturbance caused by noisy and misbehaving pupils in 2001 is in line with the results of several studies of stress among teachers (Boyle et al., 1995;

Friedman, 1995; Griffith et al., 1999; Jacobsson et al., 2001; Santavirta et al., 2001).

Not only the disrespectful pupils but also the larger groups of children taught in the classes in 2001 probably affected background noise and talking distance unfavorably and caused more adverse vocal symptoms in teachers.

One aim of the education of young children is to enhance their language development. However, poor listening conditions in the preschools and schools caused by background noise have a negative impact on the pupils’ ability to hear what is being said (Vilkman, 2004). Additionally, the results of a study By Morton and Watson (2001b) showed that children’s ability to recall words and draw final target inferences was lower if the teacher had a dysphonic voice. As pointed out by Morton and Watson (2001a), providing information on voice related issues to health care professionals, educators and administrators involved with the teaching profession is of the utmost importance, and speech therapists should play a key role in this. The Finnish Institute of Occupational Health (a research and specialist organization in the sector of occupational health and safety), has taken the initiative by arranging the first course for speech therapists specializing in occupational health in 2004. One purpose of this course was to educate speech therapists to promote improvements of the work environment, work communities and organizations in their discipline. The initiative of the Finnish Institute of Occupational Health to educate speech therapists in order to enhance occupational health safety can be regarded as an important step towards greater understanding of the voice as an occupational tool. A resent review of epidemiological and acoustic-physiological research on voice disorders by Vilkman (2004) refers to evidence provided by several studies that voice disorders should be accepted as a subcategory of occupational safety and health problems. These findings will be most beneficial for the speech therapists involved in occupational health issues related to the use of the voice as a professional tool for educators.